diff --git a/setup.py b/setup.py
index 7c355ed..f863f82 100644
--- a/setup.py
+++ b/setup.py
@@ -42,7 +42,7 @@
             'tyto>=1.4',
             'openpyxl',
             'requests',
-            'sbol_factory>=1.1'
+            'sbol_factory>=1.1',
             'pydna'
             ],
       extras_require={  # requirements for development